This invention relates to a method and an apparatus for a vehicle to get traffic information and using the information to navigate. The characteristic of this invention is that a vehicle acquires the information of traffic status in front of it by means of information transference from the passing vehicles.
Some of the prior vehicle navigation systems, presently available or under development, use satellites which allow the vehicles to identify their present location, while they do not provide traffic information. Other navigation systems, using a central computer to provide traffic information for vehicles, communicate with the vehicles through signal posts allocated along the roads. Because these systems have to build transceiver posts at many adequate locations (such as each intersection), the vehicles that are not at the fight location (such as while blocked between the intersections) can not receive the information, such systems work well only in an urban area with light traffic conditions.
The U.S. Pat. Nos. 4,513,377 of Hasebe et al.; 4,963,865 of Ichikawa et al. and 5,016,007 of Iihoshi et al. disclose display systems which can display the present position of the vehicle relative to a map on a display screen through map-matching calculations. But these systems provide only static information about the path instead of dynamic conditions of the traffic.
In the U.S. Pat. No. 4,706,086, a system for communication and signalling between a plurality of vehicles is disclosed. Each vehicle is equipped with signal receiver means, transmitter means, detectors means and a control unit. It allows the driver of the vehicle to be provided with information about the travelling conditions (tailbacks, forced stops, "road clear", fog bands, rain etc.) on the stretch of road on which he is about to travel. However, the information is only about the condition of the road straight ahead. It is not concerned with traffic problems that might be encountered when travelling over a network of interconnected roads to a particular destination.